to
the
pilot
tone.
0)
Additional
signal
on
input
St101.4b
(c).
d)
Radio
traffic
signal
on
input
St101.4a
(c).
For
the
MPX
signal
the
stage
gain
is
+6
dB
(R357
:
R325);
the
other
signals
are
not
amplified.
The
two
output
stages
MPXl
and
MPX2
are
of
identical
design.
The
emitter
follo-
wers
T155
(T158)
are
equipped
with
the
controlled
current
sources
T156/T157
(T159/T160)
acting
as
emitter
resistors.
The
capacitors
0195/0196
(0198/C199),
which
are
connected
back
to
back,
couple
out
the
MPX
signal
without
the
DC
component
and
feed
the
parallel—connected
outputs
Eu40
and
St101.7bc
(Bu50
and
St101.7ac)
at
the
rear
of
the
unit.
The
source
impedance
is
basically
the
resistance
of
R347
(R555).
4.4
Pilot-freguency
Processing
See
circuit
diagram
230.8518
S,
sheet
2,
and
oscillograms
in
Fig.
6b.
The
crystal
oscillator
QlOl/Blll
III
delivers
the
4.256-MHZ
reference
frequen—
cy
(=
2
x
8
x
14
x
58
kHz)
via
the
inverters
3111
II
and
1.
After
a
division
of
8
:
1
in
B113
1,
the
532-kHz
clock
frequency
is
available
for
the
shift
register.
From
this
frequency
the
monostable
circuit
consisting
of
T141/T142
obtains
the
slightly
delayed
sampling
pulses
for
the
sample
&
hold
circuit
T137
in
the
summing
amplifier.
The
stages
1
to
14
in
the
16-digit
shift
register
B108/BlO9
are
connected
Via
3109.12
—
G1
107
—
B108.7
so
as
to
form
a
ring.
One
bit
continuously
cycles
with
the
clock
frequency
and
thus
causes
a
"high"
level
at
the
output
assigned
to
the
corresponding
digit.
All
other
outputs
that
are
not
activated
are
at
"low".
If
there
is
no
hit
circulating,
it
is
fed
in
by
G1
111
to
G1
118
via
B111
IV
and
G1
106.
The
reset
line
B109.13
(13th
digit)
which
is
run
to
B108.6
+
.14
and
B109.6
erases
the
contents
of
the
stages
1
to
12
before
the
bit
is
transferred
to
the
first
stage,
thus
avoiding
the
circulation
of
two
or
more
bits.
Pilot-tone
generation
is
carried
out
in
two
different
ways,
depending
on
the
pilot
mode
selected
with
switch
8107;
the
shift
register
acts
as
a
14
:
1
divider.
The
signal
from
the
8th
shift
register
stage
(8108.2)
is
used
for
the
pilot
tone
with
fixed
phase.
It
is
applied
to
the
2
:
1
divider
3113
II
which
pro—
duces
a
symmetrical
squarewave
at
19
kHz.
R
38122
—
19
